Mir Mine (Russian: Кимберлитовая алмазная трубка "Мир"Kimberlitovaya Almaznaya Trubka "Mir"; English: kimberlitediamond pipe "Peace") also
called Mirny Mine was an open pitdiamond mine located in Mirny, Eastern Siberia, Russia. The mine is 525 meters
(1,720 ft) deep and has a diameter of 1,200 m
(3,900 ft),[1]
and is the second largest excavated hole in the world, after Bingham
Canyon Mine. The airspace above the mine is closed for
helicopters because of a few incidents in which they were sucked in
by the downward air flow.[2][3][4][5]

The mine was discovered on June 13, 1955 by Soviet geologists
Yuri Khabardin, Ekaterina Elagina and Viktor Avdeenko during the
large Amakinsky Expedition in Yakut ASSR. They found
traces of volcanic rock kimberlite which are usually associated with
diamonds. This finding was the first success in the search for
kimberlite in Russia, after numerous failed expeditions of the
1940s and 1950s. For this discovery, in 1957 Khabardin was given
the Lenin Prize,
which was one of the highest awards in the Soviet Union.[6][7]

The development of the mine had started in 1957 in extremely
harsh climate conditions. Seven months of winter per year froze the
ground into permafrost, which was hard in winter, but
turned into sludge in summer. Buildings had to be raised on piles,
so that they would not sink in summer, and the main processing
plant had to be built on a better ground found 20 km away from the
mine. The winter temperatures were so low that car tires and steel
would shatter and oil would freeze. During the winter, the workers
used jet engines to defreeze and dig out the permafrost or blasted
it with dynamite to get access to the underlying kimberlite. The
entire mine had to be covered at night to prevent the machinery
from freezing.[2][8]

In the 1960s the mine was producing 10 million carats (2 tonnes) of
diamond per year, of which a relatively high fraction (20%) were of
gem quality.[2] The
upper layers of the mine (down to 340 meters) had very high diamond
content of 4 carats per tonne of ore, with the relatively high
ratio of gems to industrial stones. The yield decreased to 1.5-2
carat/tonne and the production rate slowed to 2 million carats per
year near the pit bottom. The largest diamond of the mine was found
on 23 December 1980; it weighed 342.5 carats (68 g) and was named
"26th Congress
CPSU" (Russian: XXVI съезд КПСС). The mine operation was
interrupted in 1990s at a depth of 340 m after the pit bottom
became flooded but resumed later.[9][10]

The rapid development of the Mir mine had worried De Beers company, which at
that time was distributing most of the world's diamonds. De Beers
had to buy Russian diamonds in order to control the market price,
and therefore needed to know as much as possible about the Russian
mining developments. In the 1970s, De Beers requested permission to
visit the Mir mine. Permission was granted under condition that
Russian experts would visit De Beers diamond mines in South Africa. De
Beers executive Sir Philip Oppenheimer and chief geologist Barry
Hawthorne arrived in Moscow in the summer of 1976. They were
intentionally delayed in Moscow by arranging a series of meetings
and lavish banquets with Soviet geologists, mineralogists,
engineers and mine managers. When Oppenheimer and Hawthorne finally
reached the Mir mine, their visas were about to expire, so that
they could only have 20 minutes at the Mir mine. Even that short
time was sufficient to get some important details. For example, the
Russians did not use water during the ore processing at all, which
was astonishing to De Beers. The reason was that water would freeze
most of the year, and dry crushing was used instead. De Beers also
overestimated the size of the mine's pit.

The Mir mine was the first and the largest diamond mine in the
Soviet Union.[11]
Its surface operation lasted 44 years, finally closing in June
2001.[10]
After the collapse of the USSR, in the 1990s, the mine was operated
by the Sakha diamond company, which reported annual profits in
excess of $600 million from diamond sales.[12]

Currently, the mine is operated by Alrosa, the largest diamond
producing company in Russia, and employs 3600 workers. It has long
been anticipated that the recovery of diamonds by conventional
surface methods will saturate. Therefore, in 1970s construction has
started of a network of underground tunnels for diamond recovery.
Production of diamonds by this method started in 1999 and is
estimated to last for another 27 years. This estimate is based on
depth explorations down to 1220 meters. In order to stabilize the
abandoned main pit, its bottom was covered by a rubble layer 45
meters thick.[1]